Beryl: Structural refinement of a sodium-rich natural crystal from Lassur mine (Ariège, France)
Authors
J. ZUÑIGA
J. M. Amigó
Abstract
The crystal structure rehnement of a blue beryl, abnormally rich in Na, collected in the mine of Lassur (Ariege. France) has been carried out. This Na-beryl is hexagonal, space group P6/mcc with a=9.236(4), c=9.201(5) A; D,i,= ~4.74g cm-' for Z=2. From this refinement the following formula Nao.Be~A1~.~Sis0O.9i ~H. 20w as found. A substitution of Al atom by Fe atom in the octahedral site and an orientational disorder o£ the water molecules in the channels is proposed to explain the crystal stmcture of this beryl.
